Serial + Memory Card for the Microprofessor MPF-IB

Some of the recent changes:
* The monitor now can use either the DART Channel A or B, depending on a single I/O-port address,
* A four pass RAM test is introduced, which executes seven checks on each address. This will catch most RAM chip and adressing errors,
* For the MPF-I, most keys on the keyboard can be tested,
* On the hardware front, a new version of the board is on its way, using
a 16x BAUD rate clock. This should improve the (still planned) Hex-Intel transfer command.